5 September 1999 N. Nitta CHIEF OBSERVER'S REPORT for Week 36 29-Aug-99 to 5-Sep-99 GENERAL The X-ray background level was monotonically decreasing through the week as AR 8673/8674 rotated off the west limb. Towards the weekend, the solar disk was dominated by compact regions only slightly larger than pre-TRACE X-ray bright points. SXT TECHNICAL Regarding a higher threshold for the flare mode trigger, a possible effect on BCS observations was mentioned last week. Now another concern is that a later trigger of flare mode (due to a higher threshold) can reduce the possibility of observing ejecta with the flare table. In order to offset this, we may take more quarter resolution images in the FFI sequence. Bad sfd images were created because an unqualified leak image crept into the database. This is now attributed to the insufficient accuracy of orbital predictions. SXT SCIENCE Not much new stuff this week. We need more people and interactions at D-toh. For Web material see Current Week: http://isass1.solar.isas.ac.jp/sxt_co/SXTweekly.html Current Week: http://isass1.solar.isas.ac.jp/sxt_co/990903.html Index: http://isass1.solar.isas.ac.jp/sxt_co/index.html This week's science nugget shows an example of a soft X-ray brightening followed by formation of hot cusp-shaped loops about a solar radius away. CAMPAIGNS For SXT plans, see: http://isass1.solar.isas.ac.jp/sxt_co/sxt_future.html For SXT completed campaigns, see: http://isass1.solar.isas.ac.jp/sxt_co/sxt_catalog.html PERSONNEL NN arrived last weekend. SEMINARS None. SXT TABLE PLAN, WEEK 37 (6-Sep-99 to 12-Sep-99) It appears that campaign observations of Whole Sun Month 3 and the MM02 are over, judging from no more daily warnings. But it does not really affect our observations. Most of the tables are called standard, but we may continue slight modifications of the sequences, those of PFIs in particular. ________________________________#_______________________________ JST Day UT Start Time Pass Table ID Monday 6-Sep-99 02:15 2 990906 P1 ARS2 STD Tuesday 7-Sep-99 02:29 3 990906* P3 ARS1 DARK Wednesday 7-Sep-99 23:18 1 990907* P1 ARS1 DIFF Wednesday 8-Sep-99 04:26 4 990907* P4 ARS1 STD Thursday 9-Sep-99 01:14 3 990908* P3 ARS1 STD Friday 10-Sep-99 01:27 3 990909* P3 ARS1 STD Saturday 10-Sep-99 22:16 2 990910* P2 ARS1 STD * Reflecting the UT date of the first pass. This plan is subject to change. Continuing requests: KSC & SSOC Tohbans: If any KSC passes are likely to be cancelled (for example due to a typhoon) or an SXT table cannot be uploaded for some reason, please telephone and e-mail the Chief Observer immediately. (sxt_co@isass0.solar.isas.ac.jp, copy to sxt_st@flare2.solar.isas.ac.jp). SSOC Tohban: On the weekly visible diagram, please mark the official five passes first and then cross out those passes that will be given to other satellites. That way we can keep the numbering straight in the Yohkoh software system. SSOC Tohban: SXT operations do not currently include terminator off- pointing. It is unnecessary this week to ask the SXT Chief Observer for terminator off-pointing information. KSC Tohbans: In general flare mode supersedes table upload, i.e. if a flare is in progress please do not upload a new table, and contact the chief observer. Normally it is OK to go ahead with the planned table without change on the next pass, if it is available. Chief observers should keep an eye on this.